The goal of this project is to generate evidence to inform non-pharmaceutical interventions (NPIs) for pandemic influenza. We are proposing three parts to our research: 1. Preventing pandemic entry into island countries - This component would review historic evidence about successes and failures with control of the 1918, 1957 and 1968 influenza pandemics entry into island countries and lessons that can be learned from this. It would assess the feasibility of using known NPI to exclude pandemic influenza from island countries of varying size, from continental islands (Australia) to medium sized islands (NZ, Fiji), to small islands (e.g. American Samoa, Marshall Islands). This information would be incorporated into a 'threshold analysis' tool for use by health and border authorities. 2. Seasonal influenza prevalence in airline passengers - This component would measure the prevalence of influenza like illness (ILI) and infection in arriving passengers according to origins and travel times and estimate the proportion who are incubating disease. It would also assess the positive predictive value of a short screening questionnaire. 3. Seasonal influenza hospitalizations and housing conditions - This component would measure rates of hospitalization with influenza in an established cohort of 225,000 people living in public housing in New Zealand. It would specifically measure the risk of influenza in relation to age, ethnicity, socio-economic status, household crowding levels and tobacco smoke exposure. Results of these related projects would inform pandemic influenza prevention in a number of ways: -Results would support decision-making about the feasibility of preventing pandemic influenza entry into island countries and the combination of NPIs that are likely to be most effective at achieving this. - Data on the prevalence of influenza in passengers from various origins and flying times would provide an important input for decisions about the efficacy of traveler exclusion, quarantine and screening. Results could also be contrasted with the patterns seen in Northern Hemisphere sites. - Findings from the housing cohort would be used to guide advice about reducing influenza transmission in households, particularly in terms of crowding levels and exposure to active and passive smoking.